Thanks Samir for your kind reply but i have already tried that as well..
yes? set mode metafile
yes? set data
pottm2008.nc yes? set data
pottmp.2008.nc yes? let p = pottmp[y=35]
yes? let q = temperature[y=35]
yes? go variance
... Variance and Covariance: Instructions:
Use the LET/QUIET command to define the variable(s) P (and Q) as
your variable(s) of interest (e.g. yes? LET/QUIET P = u[x=180,y=0])
The variance of P will be variable P_VAR (Q --> Q_VAR)
The covariance will be COVAR The correlation will be CORREL.
Type GO VAR_N to obtain n/n+1 statistical correction factor
...
yes? go var_n
CANCEL MODE VERIFY
**ERROR: variable unknown or not in data set: TEMPERATURE[Y=35]
IF `nm1 eq 0` then exit/script
Command file, command group, or REPEAT execution aborted